Question

Which of the following is a tetrabasic acid.

• A. Orthophosphorus acid
• B. Orthophosphoric acid
• C. Metaphosphoric acid
• D. Pyrophosphoric acid

Answer 1

Answer: (D)

Pyrophosphoric acid

Answer 2

$H_{4}P_{2}O_{7}$ pyrophosphoric acid

$HO - \overset{\underset{O}{OH}}{\overset{\underset{||}{||}}{P}} - O - \overset{\underset{O}{OH}}{\overset{\underset{||}{||}}{P}} - OH$

Tetrabasic ($4 - OH$ groups)